From 1b625dab2d7b56e6b8d3289a0726724b3830e6b7 Mon Sep 17 00:00:00 2001
From: Haidong Ji
Date: Sun, 19 Aug 2018 10:48:24 -0500
Subject: GCD done!

---
 PlaygroundCpp/Sources/Playground.cpp | 62 ++++++++++++++----------------------
 1 file changed, 24 insertions(+), 38 deletions(-)

diff --git a/PlaygroundCpp/Sources/Playground.cpp b/PlaygroundCpp/Sources/Playground.cpp
index 8ef7faa..caa008b 100644
--- a/PlaygroundCpp/Sources/Playground.cpp
+++ b/PlaygroundCpp/Sources/Playground.cpp
@@ -1,59 +1,45 @@
 #include <iostream>
 //#include <gtest/gtest.h>
 
-//int get_fibonacci_last_digit_naive(int n) {
-//	if (n <= 1)
-//		return n;
-//
-//	int previous = 0;
-//	int current = 1;
-//
-//	for (int i = 0; i < n - 1; ++i) {
-//		int tmp_previous = previous;
-//		previous = current;
-//		current = tmp_previous + current;
-//	}
-//
-//	return current % 10;
-//}
+static int getGCD(int a, int b) {
+	if (b == 0) {
+		return a;
+	}
 
-int get_fibonacci_last_digit_optimized(int n) {
-	if (n <= 1)
-		return n;
-	int fibLastDigitArray[n];
-	fibLastDigitArray[0] = 0;
-	fibLastDigitArray[1] = 1;
-	for (int i = 2; i < n + 1; i++) {
-		fibLastDigitArray[i] = (fibLastDigitArray[i - 1]
-				+ fibLastDigitArray[i - 2]) % 10;
+	if (b > a) {
+		return getGCD(b, a);
+	} else {
+		return getGCD(b, a % b);
 	}
-	return fibLastDigitArray[n];
 }
-
 //TEST(FibLastDigitTest, Zero) {
-//	ASSERT_EQ(get_fibonacci_last_digit_naive(0), 0);
+//	ASSERT_EQ(getGCD(18, 35), 1);
 //}
 //
 //TEST(FibLastDigitTest, One) {
-//	ASSERT_EQ(get_fibonacci_last_digit_naive(1), 1);
+//	ASSERT_EQ(17657, getGCD(28851538, 1183019));
 //}
 //
 //TEST(FibLastDigitTest, Three) {
-//	ASSERT_EQ(get_fibonacci_last_digit_naive(3), 2);
+//	ASSERT_EQ(7, getGCD(1344, 217));
 //}
 //
 //TEST(FibLastDigitTest, Forty) {
-//	ASSERT_EQ(get_fibonacci_last_digit_naive(40), 5);
-//	ASSERT_EQ(get_fibonacci_last_digit_optimized(40), 5);
+//	ASSERT_EQ(1344, getGCD(1344, 1344));
 //}
 //
 //TEST(FibLastDigitTest, ThreeThreeOne) {
-//	ASSERT_EQ(get_fibonacci_last_digit_optimized(331), 9);
-//	ASSERT_EQ(get_fibonacci_last_digit_optimized(327305), 5);
+//	ASSERT_EQ(4, getGCD(14159572, 63967072));
+//}
+//
+//TEST(FibLastDigitTest, ReverseAB) {
+//	ASSERT_EQ(4, getGCD(14159572, 63967072));
 //}
+
 int main() {
-    int n;
-    std::cin >> n;
-    int c = get_fibonacci_last_digit_optimized(n);
-    std::cout << c << '\n';
-    }
+	int a, b;
+	std::cin >> a;
+	std::cin >> b;
+	int c = getGCD(a, b);
+	std::cout << c << '\n';
+}
-- 
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